Forming tool and method for positioning the forming tool

ABSTRACT

The forming tool is provided for sheet-metal components and embodied in particular as a forming gripper. The forming tool can be positioned and handled in an automated manner by an industrial robot system. The forming tool has a component-probing system, which contains a probing element that is displaceable upon contact with the component. The displacement of the probing element can be ascertained by a measuring system. Furthermore, a suitable method for positioning the forming tool is provided.

The invention relates to a forming tool for sheet-metal components, inparticular a forming gripper, wherein the forming tool can be positionedand handled in an automated manner by means of an industrial robotsystem, according to the preamble of claim 1.

Furthermore, the invention relates to a method for positioning theforming tool according to the preamble of claim 11.

Forming tools of the type mentioned at the outset are known. Forexample, DE 299 18 486 U1 discloses a device for positioning finishedsheet-metal pressed panels and a robot-guided manufacturing tool. Thesheet-metal pressed panels are vehicle body parts. The exact actualposition of the sheet-metal pressed panel inside the working space ofthe industrial robot in relation thereto is thereby determined. In thearea of a support of the manufacturing tool a sensor is provided, whichdetects a contact by the support with the sheet-metal pressed panel andtransmits corresponding signals to a control to stop the shifting of thesupport.

The object of the invention is to propose an alternative forming tool.

Furthermore, it is the object of the invention to disclose a suitablemethod for positioning the forming tool.

The object is attained with a forming tool with the features of claim 1.The forming tool according to the invention is characterized in that ithas a component-probing system, which contains a probing element that isdisplaceable upon contact with the component, the displacement of whichprobing element can be ascertained by means of a measuring system. Theforming tool is characterized by a relatively simple structural designand permits a reliable positioning relative to the sheet-metal componentby means of an industrial robot system, the exact position of whichsheet-metal component in the space does not have to be precisely knownfor forming. As soon as a contact with the component in the form of adisplacement of the probing element is ascertained by means of themeasuring system, the precise tool position can be determined and thusalso the precise component position in the space. The probing operationis thus indirectly used in addition for determining the componentposition in the space. It is thus possible by means of the forming toolto carry out a precise forming process with a sheet-metal component, theposition of which in the space was not initially sufficiently known.Both the positioning as well as the handling of the forming tool arethereby carried out in an automated manner by means of the industrialrobot system. The forming tool can be in particular an embossing and/orstamping gripping device. The probing element is preferably displaceableagainst an elastic restoring force.

The probing element is preferably arranged in a die unit of the formingtool. It is possible through this to create a contact between thedisplaceable probing element and the sheet-metal component in the directforming area of the forming tool. During the production of this contact,the forming tool is located in a precise probing position that can bedetermined by the industrial robot, from which position subsequently anaccurately positioned forming starting position of the forming tool canbe adopted relative to the component. This renders possible areproducibly precise forming process on a respective component, theprecise position of which in the space does not have to be exactly knownfor this purpose.

Advantageously, in the probing position the probing element projects onthe front face outwards beyond the die and is rigidly connected to areference element arranged in the die unit in a defined manner. Due tothe functional and spatial separation of the probing element and thereference element, it is possible to carry out the actual measuringoperation undisturbed by the probing operation. Since the probingelement is rigidly connected to the reference element, a displacement ofthe probing element is transmitted precisely and directly to thereference element, so that the displacement of the probing element canbe determined at the same time by means of the measuring system.

In the probing position, the probing element can project on the frontface from the die by a defined probing length. The probing length isthus a safety distance of the die relative to the sheet-metal componentafter production of a contact of the probing element with the samecomponent. The speed of the forming tool approaching the component can,if necessary, be greater up to the production and verification of acontact between the probing element and the component than during thiscontact until adoption of a defined forming starting position, i.e.,during production of the contact between the die and the component withcompletely retracted probing element and forming not yet started. Atthis time the probing length is zero, since the probing element is fullyretracted into the die against the elastic restoring force. Withcorresponding handling of the forming tool by means of the industrialrobot system, the actual forming process of the sheet-metal componentcan then take place. The contact of the probing element is used forascertaining the precise position of the component relative to theforming tool while at the same time ensuring a sufficiently largeprobing length, i.a., to avoid an undesirable collision between the dieof the forming tool and the sheet-metal component.

The reference element and the measuring system are preferably arrangedin a measuring area spaced apart from the forming area. This renderspossible the use of a relatively robustly embodied probing element inthe forming area and at the same time of a geometrically very preciselyembodied sensitive measuring system in the spaced apart measuring area.The forming tool can thus be characterized by an adequate robustness inthe forming area and at the same time by a measuring precision that canbe reproduced free of disturbances.

The reference element preferably has a reference surface that isarranged at a defined measuring distance from the measuring system. Themeasuring system thereby preferably contains a distance sensor, whichcan be operatively connected to a control unit of the industrial robotsystem. A forming tool of this type is characterized by a structurallyrelatively simple design and is suitable for use in particular in anautomated series production due to its reliable positioning and handlingability.

The measuring distance is advantageously greater than the probing lengthby at least a defined forming path. This makes it possible to measure adisplacement of the probing element during the probing operation bymeans of the measuring system and immediately afterwards also theforming path during the forming operation on the sheet-metal component,since the probing element is displaced further against an elasticrestoring force together with the die during the forming operation. Thisdisplacement can also be measured if necessary continuously by means ofthe measuring system within the measuring distance.

The forming tool can additionally be embodied as a stamping tool, theprobing element having at the same time the function of a stamp, whichafter a stamping can be forcibly moved away from the component by meansof a displacement system. This renders possible a correct opening of theforming tool after completion of the forming/stamping operation.

Furthermore, the object is attained through a method with the featuresof claim 11. The method according to the invention is characterized inthat the forming tool is moved towards the component until theproduction of a contact between a probing element and the component, adisplacement of a probing element from a defined probing position beingmeasured by means of a measuring system to determine the exact positionof the forming tool relative to the component. Before production of acontact with the component, the probing element thereby projectsoutwards on the front face beyond the die by a defined probing length.By means of the method it is possible to achieve the advantagesmentioned above with respect to the forming tool.

The forming tool in addition can have a stamping function, and theprobing element can at the same time have the function of a stamp. Afterstamping in the component has been completed, the stamp can thereby bemoved away from the component forcibly by means of a displacementsystem. Several processing functions can thus be carried out on acomponent by means of the forming tool.

After forming on the component has been completed, the industrial robotsystem can move the forming tool away from the component and at the sametime the forming stamp can carry out a movement relative to the die unitcompensating for the movement of the forming tool, so that the formingstamp is continuously in contact with the component and the die unit ismoved away from the component, relieving the forces acting on thecomponent through it. Due to the relief defined with respect to theopening movement of the forming tool of those forces that act on theformed component through the closed forming tool, an undesirablerecovery in the forming area of the component during opening of theforming tool can be avoided or at least restricted while guaranteeing aparticularly high forming precision on the component.

Further advantages of the invention are shown by the specification.

The invention is explained in more detail based on a preferred exemplaryembodiment with reference to a diagrammatic drawing.

They show:

FIG. 1 A diagrammatic side view, partially in longitudinal section, of aforming tool according to the invention with the probing element incontact with a component,

FIG. 2 The forming tool of FIG. 1 during the forming/embossing operationand

FIG. 3 The forming tool of FIG. 2 after the forming/embossing operationand in opened operating position.

FIG. 1 shows in diagrammatic form a forming tool 10, which is embodiedas connectable to an industrial robot (not shown in the Fig.). Theforming tool 10 can be a forming gripper and in particular an embossinggripper and/or a stamping gripper. For the automated positioning of theforming tool 10 by means of an industrial robot, the forming tool 10 isprovided with a component-probing system 12, which contains a probingelement 14. To this end the probing element 14 projects by a definedprobing length B on the front face beyond the forming tool 10. By meansof the component-probing system 12, it is possible to position theforming tool 10 in an automated manner relative to a sheet-metalcomponent 16, wherein for this purpose the precise spatial position ofthe forming area of the component 16 does not need to be exactly known.The probing element 14 is arranged concentrically integrated in a dieunit 20 such that it is displaceable (according to double arrow 42) tothe right in the drawing plane (against an elastic restoring force of acompression spring 36). The die unit 20 furthermore contains a die 22,which concentrically encloses the probing element 14 and is held in aseating slot of a back rest 30 by means of compression springs 32. Thetongs-shaped forming tool 10 furthermore contains a forming stamp 40,which with the die unit 20 forms an interstice in which after the roughpositioning of the forming tool 10 by means of the industrial robot hasbeen completed, the forming area of the sheet-metal component 16 lies.During the actual forming process the forming stamp 40 is moved againstthe die 22 to the right in the drawing plane.

The forming tool 10 is furthermore provided with a measuring system 18that contains a distance sensor 28, which can be embodied an analogsensor. The probing element 14 thereby extends from the forming area ofthe forming tool 10 along the die 22 up to a measuring area in which areference element 24 is arranged, which is rigidly connected to theprobing element 14. The reference element 24 contains a flat referencesurface 26, which lies at a defined measuring distance A relative to thedistance sensor 28 at the probing element 14 lying in the probingposition according to FIG. 1. In this probing position the probingelement 14 projects on the front face outwards beyond the die 22,forming a defined probing length B relative to the front face of the die22. This probing position results automatically as the normal positionthrough the spring force of the compression spring 36 acting on theprobing element 14 by means of a stud 34. The probing element 14 isthereby pressed by the acting spring force against a face of adisplacement element 44 arranged in a defined displaceable manner in thedie unit 20. Finally, FIG. 1 also shows a connection stamping cylinder38.

After determining a displacement of the probing element 14—and thus alsoof the reference element 24—by means of the distance sensor 28 due tothe beginning reduction of the measuring distance A, the correspondingdata, namely the respectively exact moment of the start and of the endof the displacement of the probing element 14, are transmitted to acontrol unit of the industrial robot, by means of which the exactspatial gripper position at the start of the contact and thedisplacement path already covered by the probing element 14 (to theright in the drawing plane) can be determined. The exact spatialposition of the forming area of the component 16 can thereby also bedetermined by means of the control unit of the industrial robot and thepath yet to be covered by the die unit 20 and forming stamp 40 relativeto the component 16 to adopt a correct forming position.

Subsequently, the industrial robot positions the forming tool 10 up tothe production of a contact of the back rest 30 with the component 16,the position path of the forming tool 10 yet to be covered now beingexactly known. Upon contact of the back rest 30 with the component 16,the probing element 14 is completely retracted into the die 22. In thisdefined forming position of the die unit 20, the forming stamp 40 ismoved against the component 16 (to the right in the drawing plane) and,in cooperation with the fixed back rest 30 and the die 22 that can bedisplaced to the right against the elastic restoring force of thecompression springs 32, brings about a correct forming in the component16. The forming stamp 40 cooperating with the die 22 thus presses withits front face the deforming portion of the component 16 into a cavitylimited circumferentially by a back rest 30, which cavity is releasedaccording to the starting axial displacement of the die 22 in the dieunit 20. The back rest 30 is positionally stable during the actualforming process, i.e., arranged immovably. This forming is shown in FIG.2.

To carry out the additional stamping operation in the component 16, theprobing element 14, which at the same time has the function of a stamp,is moved by means of the connection stamping cylinder 38—with theinterconnection of a power transmission system 48 connected to the stamp14 by a stop 46—into a defined stamping position—according to FIG. 2 tothe left in the direction of component 16. The stamp 14 thereby movesrelative to the displacement element 44 fixed during this operation. Thecomponent 16 is now formed as well as provided with a stamping by meansof the forming tool 10 according to FIG. 2.

To open the forming tool 10, the stamp 14 is moved to the right in thedrawing according to double arrow 42, i.e., away from the component 16,by means of the displacement element 44 in cooperation with theconnection stamping cylinder 38, while at the same time or subsequentlythe forming stamp 40 is moved according to the double arrow 50 to theleft in the drawing, i.e., likewise away from the component 16. At thesame time the back rest 30 fixed relative to the industrial robot ismoved a little to the right by means of a movement of the industrialrobot according to the double arrow 52 in the drawing, i.e., also awayfrom the component 16. The die 22 is thus moved in its stop positionrelative to the back rest 30 due to the acting elastic restoring forceof the compression springs 32. This resulting opening position of theforming tool 10 is shown in FIG. 3.

To position the forming tool 10 by means of an industrial robot, thesame is moved towards the component 16 until the production of a contactbetween the probing element 14 projecting by the probing length B andthe component 16. This specific moment during the positioning of theforming tool 10 is shown in FIG. 1. With a further relative movement ofthe die 22 with the concentric probing element 14, a displacement of theprobing element 14 occurs against an elastic restoring force accordingto double arrow 42 in the drawing plane to the right. This leads to acorresponding displacement of the reference element 24 located in themeasuring area, so that a reduction of the probing length B in theforming area causes a corresponding reduction of the measuring distanceA in the measuring area. This change in the measuring distance A isdetermined precisely and simultaneously by the distance sensor 28, sothat a controlled positioning of the forming tool 10 relative to thesheet-metal component 16 can occur such that the free front face of theback rest 30 can be brought in a controlled manner into contact with thesheet-metal component 16 to be formed. At this moment the probingelement 14 is completely retracted into the die 22.

If the measuring distance A is larger than the probing length B at leastby a defined forming path, the joint displacement of the probing element14 together with the die 22 and thus the forming path resulting on thecomponent 16 via the change of the measuring distance A due to thecorresponding displacement of the reference element 24 can be directlyascertained by means of the distance sensor 28 even during the actualforming process. Thus the forming height (e.g., the embossing height)achieved on the component 16 in addition can also be detected by meansof the distance sensor 28.

Thus after a robot-guided approach movement of the forming tool 10(optionally at increased speed), a first contact between the probingelement 14, which at the same time has the function of a stamp, and thecomponent 16 is detected by means of the measuring system 18. Thefurther traversing movement can then first be stopped or also onlyslowed down. The remaining residual traverse for positioning the formingtool 10 and for carrying out the forming operation is ascertainedexactly by means of the control unit of the industrial robot. To placethe back rest 30 against the component 16, an automated advance of theresidual traverse occurs in particular at creep speed, i.e., at reducedspeed, to increase the approaching and thus the positioning precision. Arepeated measurement with correspondingly repeated position correctionof the industrial robot can thereby optionally also take place. Due tothe in principle mechanical approach probing of the component and thusdetection of the component position in the range of action of theforming tool 10, a particularly high positioning reliability of the samecan be achieved with components associated with positional tolerance(components with non-exact spatial position).

After component forming has been completed, the industrial robot movesthe forming tool 10 away from the component 16. The forming stamp 40 atthe same time performs a movement relative to the die unit 20compensating for the movement of the forming tool 10, so that theforming stamp 40 is continuously in contact with the component 16, andthe die unit 20, relieving the forces acting through it on the component16, is moved away from the component 16. Through this an undesirablerecovery in the forming area of the component 16 during opening of theforming tool 10 is avoided or at least restricted while guaranteeing aparticularly high forming precision on the component 16. The formingtool 10 can subsequently easily be opened to completely release thecomponent 16.

1-14. (canceled)
 15. A forming tool for a sheet-metal component, whichis positioned and handled in an automated manner by an industrial robotsystem, comprising: a component-probing system including a probingelement that is displaceable upon contact with the component; and ameasuring system configured to ascertain the displacement of the probingelement.
 16. The forming tool according to claim 15, wherein the probingelement is displaceable against an elastic restoring force.
 17. Theforming tool according to claim 15, wherein the probing element isarranged in a die unit of the forming tool.
 18. The forming toolaccording to claim 17, wherein, in a probing position, the probingelement projects on a front face outwards beyond the die and is rigidlyconnected to a reference element arranged in the die unit in a definedmanner.
 19. The forming tool according to claim 18, wherein, in theprobing position, the probing element projects on the front face fromthe die by a defined probing length (B).
 20. The forming tool accordingto claim 18, wherein the reference element and the measuring system arearranged in a measuring area spaced apart from a forming area.
 21. Theforming tool according to claim 18, wherein the reference element has areference surface that is arranged at a defined measuring distance (A)from the measuring system.
 22. The forming tool according to claim 15,wherein the measuring system contains a distance sensor, which isoperatively connected to a control unit of the industrial robot.
 23. Theforming tool according to claim 21, wherein the measuring distance (A)is greater than a probing length (B) at least by a defined forming path.24. The forming tool according to claim 15, wherein the forming tool isembodied as a stamping tool and the probing element has at a same time afunction of a stamp, which after a stamping can be forcibly moved awayfrom the component by a displacement system.
 25. A method forpositioning a forming tool by an industrial robot relative to acomponent, the position of which is not exactly known at least in aforming area, comprising: moving the forming tool towards a componentuntil a production of a contact between a probing element and thecomponent; and measuring a displacement of the probing element from adefined probing position by a measuring system to determine an exactposition of the forming tool relative to the component.
 26. The methodaccording to claim 25, wherein the forming tool includes a stampingfunction, and the probing element at a same time has a function of astamp.
 27. The method according to claim 26, wherein after stamping hasbeen completed in the component, the probing element is forcibly movedaway from the component by a displacement system.
 28. The methodaccording to claim 25, wherein after processing of the component hasbeen completed by the forming tool, the industrial robot system movesthe forming tool away from the component and at a same time a formingstamp carries out a movement relative to the forming tool therebycompensating for the movement of the forming tool, such that the formingstamp is continuously in contact with the component and a die unit ismoved away from the component relieving forces acting on the component.29. A forming tool, comprising: a component-probing system having aprobing element projecting by a defined probing length B on a front facebeyond the forming tool; a measuring system that contains a distancesensor which is configured to determine a displacement of the probingelement; and a reference element containing a reference surface whichlies at a defined measuring distance A relative to the distance sensorat the probing element lying in a first probing position; wherein themeasuring system determines a displacement of the probing element by thedistance sensor due to a beginning reduction of the defined measuringdistance A.
 30. The forming tool according to claim 29, wherein, in theprobing position, the probing element projects on the front faceoutwards beyond the die, forming the defined probing length B relativeto the front face of the die, and the probing position resultsautomatically as a normal position through a spring force of acompression spring acting on the probing element by a stud.
 31. Theforming tool according to claim 29, wherein after determining adisplacement of the probing element by the distance sensor due to abeginning reduction of the defined measuring distance A, the exactmoment of start and of end of the displacement of the probing elementare transmitted to a control unit of the industrial robot, by which anexact spatial gripper position at the start of contact and thedisplacement path covered by the probing element is determined.
 32. Theforming tool according to claim 29, wherein the probing element isarranged concentrically integrated in a die unit such that it isdisplaceable against an elastic restoring force of a compression spring.33. The forming tool according to claim 29, wherein the forming tool isat least one of an embossing gripper and a stamping gripper.